Electrical transformer



' Acz. M. WELCHY July 6, 1926.

ELECTRICAL TRANSFORMER Filed Oct. 24, 1921 I I l INVENTOR R7' SmPatented July 6, 1926.

UNITED STATES CHARLES M. WELCH, OF OGDENfARKANSAS.

ELECTRICAL TRANSFORMER.

Application filed October 24, 1921. Serial No. 510,170.

My invention `pertains to improvements in electrical transformers, inwhich the active elements consisting of induction coils with suitableinsulating material and magnetic cores, are operated in a body ofinsulating fluid within a containing case having supporting means andwith outlets to the supply and service connections.

rlhe object of my improvement is:

(l) To provide a light weight, safe, durable and efficient construction,plain, `sensible and rugged, and easy to build at a reasonable cost.

(2) To render the terminals more convenient and secure in making serviceconnections to meet developments in the art of electric wiring.

(3) 'Io secure a simple positive support for the core and coils formaking the various parts safe in handling in transportation, removingany possibility of mechanical strainV on the insulation, and renderingthe parts accessible in manufacture and repair.

(4) To provide a transformer which can be shipped with the case filledwith insulating fiuid. This is intended to protect the coils againstabsorbing moisture from the atmosphere as often occurs when transformersare shipped dry in an ordinary case.

(5) To secure the abolishment of cast iron in the construction. Castiron is a poor conductor of heat and breaks easy in handling.

(6) To do away with all tap connections with no looseparts inside thecase.

(7) To standardize a line of distributing transformers to maintain auniform voltage.

(S) To secure a combination structure that will permit design andsuccessful manufacture of small high tension units.

I attain the object by the arrangement illustrated in the accompanyingdrawings, in which:

Fig. 1, is a vertical section of the entire transformer. Fig. 2, is atop View. Fig. 3, shows a back view, -Fig. l, is ahorizontal crosssectional elevation taken at approximately thc center of the.arrangement shown in Fig. l, and shows the arrangement of the coilsaround the core.

Similar letters refer to similar throughout the several views.

These drawings illustrate a transformer of simple cylindrical likepattern, in which parts irregular form has been avoided. The con--taining case is made up of two parts, a formed sheet steel body A., anda boiler plate top` cover piece B. A gasket C, rest-s" be- -ween the topflange of the steel vbody and the top cover piece. The gasket, isclamped by the holding bolts D, which prevents breathing action fromdrawing moisture in the case. The low tension leads E, pass vthrough apipe F, fitted in the top cover piece. To the pipe F, is fitted a Ushaped hollow metal piece Gr, having a porcelain terminal entrance undera protecting iron hood forming an outlet to the service connection. Thespace around the leads in the pipe F, is filled with an oil and moistureproof solid compound thus sealing the outlet excepting by the electricalconnection. The high tension leads I, issue from the case through asimilar arrangementr with the pipe F, for the more moderate highpotential systems. This construction of the formed outlets assumes thesupply and. service lines are carried in the open, but, the. convenienceand safety in joining conduit pipe directly to the pipe F, is obvious toany one skilled in the art of electrical wiring. In practice where atransformer is placed between the various wiring systems in use therearises the necessity of employing various adapting devices'which`greatly increases the expense of the work and complicates the system.My transformer in the arrangement of the terminals is novel anduseful ineliminating` these difliculites.

For the higher potential systems I employ a high tension insulatorconstruction vJ, similar to pot head or cable terminal work. The lowerpart of the insulator vcarrying the high tension lead from thetransformer coil is hermctically sealed and fastened in the top coverpiece B, through the pipe K, with the inner end of theinsulatorprojecting under the insulating yfluid and the outer end extended andspaced for the required test voltage. A porcelain rain cap is providedwhich isshipped separate from the transformer preventing possible damagein transit.V The rain cap has large fluted surface which effectivelysheds all water.` A vportion of the high tension cable is hermet-Vically sealed in` theL cap for connection to the line. Connectors areprovided in the cap and in the stem 1n the top cover piece B, forming ameans for readily disconnect- Cit Cill

ing the circuit When necessary. T he cap should be handled with tongs onlive circuits.

A lifting ring L, is attached in the center of the top cover piece whichbeingthe approximate center pointof gravity, holds the transformer inline when being raised to the cross arms.

The top cover piece B, provides a support to which the core M, and thecoils N, are suspended and held by means of core clam-ps O, having oneof their sides fastened directly to the cover.

Lugs P, are fastened to the top and bottom of the containing casetewhich lugs pole hangers Q, are secured for attaching the transformer tocross arms.

The case has at the bottom a valve R, for draining ivatery fluid fromthe isolating chamber S. The isolating chamber is formed by 'placing aninclined shelf T, with an aperture U, in the loiver part of the case. yAny water in the fluid ivill settle by gravity to the shelf T and dripthrough the small aperture U into t-he isolating chamber S Where it isprevented from circulating into the main body of insulating fluid, as ismore fully described and claimed in my application #495,522 lilcd august25, 1921, covering improvement in transformers.

insulating fluid may be placed in the case by means of removing a pipeplug V. in the top cover piece B. A pct cock lV, indi- Cates by overflowwhen a sutlicient amount ofrlui'd is in the case. A relief pressurevalve X, is fastened in the top and is set for a dangerous pressureinside but it is not intended for the valve to act as a breather sincethe construction tlnoughout is dcsigned to prevent drawing moisture intothe case by breathing; action. A suitable name plate Y, of stampedmaterial is secured to the case.

The coils N, are cylindrical like in shape and are Wound on a roundWinding form. A round cylindrical. coil secures in Winding 'an equaltension oi' the ivire at all points ivith an absence of corners whichbreak the insulation. The uniform tension throughout the coils rendersalso a uniform eXpansion of parts under heat` and saves the insulationfrom injury. The windings are divided into thin coil sections which aresecured by placing treated spacers with suitable insulation betiveen theconcentric coils and between the concentric coils and the core, theprocedure being to Wind the Wire tightlyover these spacers and treatingthe finished sections by the vacuum drying and insulating process whichrenders the insulation more impervious to moisture. I use commercialmaterials for insulating but I limit the use of fibre insulations asthey are non-conductors of heat. I secure a better self cooling effectby providing an open structure with ample fluid ducts. in theseparticulars the form of the coils and core employed in my transformerare of pa'amount consideration in securing the objects set fort-h.

rThe core of the magnetic circuit is con structed of laminated materialassembled with the laminatioiis on a plane with a right angle to theaxis of the coils and closed through a common single yoke. By thisarrangement the assembled laminations are clamped securely on parallelsides and fastened directly by theclamping means to the top cover pieceivhich therebyv suspends the coils in the fluid in such Yfashion as tosccure a it'ree circulation of the fluid to all the active parts.

Transformers of the soscalled tiro limb core type' are commonly employedin the smaller sizes and higher voltages. and it has heretofore beenconsidered impractical to build a closer approach to the shell type forsuch work. in my transformer the core section is increased over the tivolimb type ier a given rating and by so doing` l dccre so theconvolutions of nire resulting in sonic increase in the core uf'eightivith a reduced copper Weight also. By placing lan'iinations ofdifferent Widths in the core l am able to utilize a very large part ofthe av;..ible core area in active core material which i. can operate ata moderately high magnetic density by reason of the conveniencepri-Psented of incri-asinp` the area in the yoke. This enables me togive ample room for my coil spacing ivith no impairment oi regulation orefhciency. Instead of joining up the core with the yolie by interleavedend members of a common length, l use a uniform length interleaving onthe yolre side and vary the length. of the end men'ibers'interleaving onthe core side, which produces a shape in the yoke that is convenient toassemble and iusulate around the coil and vfhich prese! i chamferedsection that secures the mmamum distribution of the nnrgnetic linxthrough the yoke with an absence ot" dead corners.

On account of limited space in small high voltage transformers, the useot terminal blocks with tap connections thereon are rcsponsible for manypotential flash-overs and break downs. hiloreover, poor linei:oiif;,ti'u tion causing unreasonable voltage drop, involving the useoil' distribution transformers having poor inherent reeul'ation (anatural result ivith the tivo limb core tyiie) with the use of tapconnections to boost the voltage is a reprehensible method ofdistribution. The usual thing with such systems is an abnormally highvoltage on light load With the voltage aboutnormal on moderate load butfalling too loiv on heavy load. Moreover, the paralleling,interconnecting, and joining transformers in multiples on polyphaselines introduces dangerous hazards if the distribution transformerratios are even slightly varied by using tap connections. In order toprovide a method of maintaining a more uniform and constant voltage onthe distribution system using my transformers, I have fixed a ratiobetween the primary and secondary windings to secure the followingresults.

(a) Systems maintaining a high primary voltage, can secure approximately120 volts secondary or multiples thereof.

(b) Systems maintaining a moderate primary voltage can secureapproximately 115 volts secondary or multiples thereof.

(c) Systems maintaining a moderately low primary voltage can secureapproximately 110 volts secondary or multiples thereof.

These transformer ratios I have proportioned for the various commercialprimary systems as follows:

volts-transformer volts-transformer volts-transformer volts-transformervolts-transformer volts-transformer ratio, Y volts-transformer ratio,volts-transformer ratio, 280:

This standardization of ratios ratio, ratio, ratio, ratio, ratio, Y

and and and and and a nd and Handen-WAHM is vital to show how I am ableto do away with all non-capillary in extending them through the coverabove the fluid level.

What I claim is:

l. The combination with a fluid insulated self cooled transformer, ahanger support on the back thereof, a transformer cover supported by aforward projecting means from the said back hanger support, core clampsengaging the cover, a transformer comprising a core secured bycompression means clamping the core between the said core clamps, with aconduit pipe in the cover, and a plurality of leads connected to theterminal conductors leading upwardr through the conduit pipe in thecover.

2. The combination with a fluid insulated self cooled transformer, ahanger support on the back thereof, a transformer cover supported by aforward proj ecting.l means from the said back hanger support, coreclamps engaging the cover, a transformer comprising a core secured bycompression means clamping the core between the said core clamps, with acore medium of the single magnetic circuit type in which a complete setof coils are wound on a common core leg having only one enclosing yoke,and round cylindrical shaped coils placed on the said core leg,substantially as described for the purpose of securing a simpleconstruction.

8. The combination with a fluid insulated self cooled transformer, ahanger support on the back thereof, a transformer cover supported'by aforward projecting means from the said back hanger support, core clampsengaging the cover, a transformer comprising a core secured bycompression means clamping the core between the said core clamps,terminal outlets through the cover, a casing holding all the necessaryfluid around the transformer, and a detachable means adjacent the upperend of the casing attaching the casing to the said back hanger supportedcover, for providing a means of securing the transformer in a suspendedmanner from the back hanger supported cover whereby the casing may bedetached and removed from around the transformer pro-per in manufactureand in case of inspection and repair on the line. c

a. The combination with a fluid insulated self cooled transformer havinga cover supported by a back hanger, a transformer comprising core andcoils and terminals, means engaging portions of the transformer casingrendering the casing fluid tight, means engaging the terminals and thecasing effectively sealing the terminals in the casing excepting theelectrical connection whereby all of the necessary fluid may be shippedin the casing with the transformer, and a means providing switchinsulators comprising an insulator portion adapted to be hcrmeticallysecured in the cover of the casing with a detachable rain cap which maybe shipped separate from the 'transformer' for providing a means todisconnect the transformer from circuit and reduce theVL liability ofdamage to porcelain parts in shipment.

In testimony I afliX my signature.

CHARLES M. WELCH.

